Basting thread with reducing shrinkability and high solvent reactivity and method of producing the same

ABSTRACT

A polycarbonate basting thread which has high solvent reactivity to perchlorethylene and a reduced shrinkability when subjected to heat is disclosed. A process for manufacturing the thread is described.

United States Patent 1191 Myers BASTING THREAD WITH REDUCING SHRINKABILITY AND HIGH SOLVENT REACTIVITY AND METHOD OF PRODUCING THE SAME [75] Inventor:

[73] Assignee: Fibrex C0rp., Humacao, RR.

[22] Filed: Aug. 18, 1972 [21] Appl. No.: 281,957

Homer S. Myers, Santurce, RR.

52 us. c1. 57/140 R, 57/157 s, 264/210 F, 264/290 51] 1111. C1 ..D02g 3/46, D02j 1/22, D01d 5/16 [58] Field of Search 264/210, 290, 235, 342, 264/346; 28/57, 71.3, 72, 72.17, 76; 57/140 R, 157 R, 157 S Sept. 17, 1974 [56] References Cited UNITED STATES PATENTS 3,214,500 10/1965 Mucsov ct a1 264/210 R 3,311,928 4/1967 Werth, Jr. et a1 2/243 R 3,329,755 7/1967 Reichul'dt et a1 264/210 F 3,373,471 3/1968 Myers 2/243 R Primary Examiner-John W. Huckert Assistant Examiner-Charles Gorenstein Attorney, Agent, or FirmWilliam E. Sherwood [5 7 ABSTRACT A polycarbonate basting thread which has high solvent reactivity to perchlorethylene and a reduced shrinkability when subjected to heat is disclosed. A process for manufacturing the thread is described.

4 Claims, 5 Drawing Figures PIUENTEDSEPI mm.

FIG. 2A

' FIG. 3A

FIG. 3

BASTING THREAD WITH REDUCING SHRINKABILITY AND HIGH SOLVENT REACTIVITY AND METHOD OF PRODUCING THE SAME BACKGROUND OF THE INVENTION In the manufacture of clothing wherein basting threads, which are to disintegrate in the presence of dry cleaning solvents, are to be employed, it is found that certain exacting requirements must be met by the inherent properties of the thread if fully satisfactory results are to be obtained. The patent to Werth et al., U.S. Pat. No. 3,311,928 indicates, for example, that merely being soluble in dry cleaning solvents and insoluble in water does not necessarily make a plastic basting thread suitable for general use particularly when the thread is wiry. Moreover, these patentees taught that when using polycarbonate thread of the present type having a diameter of 0.010 inch sewn with a sewing machine, a tensile strength of about 8,500 psi was desirable when chain basting, as at the edges of flaps, collars and coats, was to be performed. Significantly, these patentees also taught that their polycarbonate thread would not be soluble in perchlorethylene or carbon tetrachloride within a suitable period of time and likewise failed to attach importance to the draw ratios in their thread manufacturing process or to the shrinkability of the thread.

Later, as disclosed in Myers U.S. Pat. No. 3,373,471 it was discovered that polycarbonate thread of the present type would fracture at certain points along its length (adjacent those points where it has received stresses from the sewing apparatus) when brought into agitated contact with perchlorethylene for at least four minutes of time. However, in this situation the thread had been stretched to about twice its extruded length and had acquired a tensile strength of about 30,000 psi, but in practice was found to fracture with jagged edges, as later to be described.

In addition, practical experience with the thread of the Myers patent indicated that some means should be employed to reduce the inherent shrinkability of the thread, and research to this end led to the filing of patent application Ser. No. 799,616 (now abandoned).

The manufacture of filaments of the polycarbonate 2,2-(4,4'- dihydroxydiphenyl) propane for use as yarn in clothing manufacture was taught by Maerov et al., U.S. Pat. No. 3,214,500 and the undesirable characteristic (for yarn usage) of the same to react with dry cleaning solvents was deliberately overcome by drawing a spun filament with a draw ratio of at least 4.0 and thereafter threating the crystallized filament with a solvent, such as acetone, which would induce crystallization faster than the solvent could dissolve the thread. By contrast, the present invention, although using the same polycarbonate material as Maerov, is for the purpose of increasing the reactivity to a dry cleaning solvent.

SUMMARY to between 85-150 percent of its original length represents the present invention.

Among the objects of the invention are the provision of a basting thread which rapidly disintegrates in perchlorethylene; the provision of a basting thread which possesses a reduced shrinkability when heat is applied thereto; the provision of an improved basting thread which fractures with relatively smooth edges when in contact with perchlorethylene; the provision of a soft basting thread which is not wiry and which'is readily sewn with sewing machines in the making of various bastes including chain stitch machines making edge bastes; the provision of a soft basting thread having a uniform diameter substantially devoid of nodular portions; the provision of a method for manufacturing basting thread with a reduced amount of apparatus as compared with conventional methods; and the provision of a relatively inexpensive method of manufacturing basting thread.

These and other objects and advantages of the invention will become more apparent as the description proceeds and when considered in conjunction with the accompanying drawing in which;

FIG. 1 is a diagrammatic view of an apparatus suitable for carrying out the manufacture of the thread.

FIG. 2 is a view of an enlarged section of conventional thread indicating the jagged nature of the break when suspended by a weight in a bath of perchlorethylene.

FIG. 2A is a view similar to FIG. 2 and indicating the nature of the break of the present thread under similar conditions.

FIG. 3 is a view indicating the stressing of a loop of conventional thread during the sewing operation; and

FIG. 3A is a view indicating the nature of the break of the thread of FIG. 3 when brought into contact with perchlorethylene.

Referring now to FIG. 1, a quantity of the polycarbonate available from Mobay Chemical Co. sold under the trademark Merlon or from General Electric Co. sold under the trademark Lexan is fed from hopper 10 into a conventional extruder 11 where it is heated to about 520F. to form a molten fluid mass having not more than about 0.1 percent moisture by weight. This material comprises the polycarbonate 2,2,-(4,4- dihydroxyphenyl) propane with the following structural formula;

CH; (H) ag -j CH3 is From the spinerette portion of the extruder a plurality of filaments 12 move downwardly (for convenience a single filament 13 being shown leaving the plenum chamber portion of the extruder) and undergo a plastic flow deformation under the influence of gravity. As an example, it is found that if the filament extruded initially with a diameter of 0.040 inch is allowed to fall freely at room temperature for about 8 feet, its diameter will be reduced to about 0.017 inch merely by the weight of the hanging filament which at this stage may be called an intermediate. Such a filament falling from the spinnerette can be elongated by percent of its original length before breaking when stretched in a conventional testing machine using standard techniques.

As used herein the term extension to break signifies the percentage of the original length of a test sample by which the length of the filament has been increased by stretching at the time of break by application of an even loading in a testing machine.

This filament, moreover, when immersed in perchlorethylene, reacts with the solvent and disintegrates almost instantly. For example, such an intermediate with a denier of 1,318; a strength of 0.80 gram per denier; and a tensile strength of 14,000 psi could possibly be employed as a basting thread, but with the likelihood that its diameter would not be uniform due to nodular portions forming therein as a result of the plastic flow which has occurred. As will be understood, a thread having such nodules may give rise to thread breakage as the nodule encounters mechanical resistance in passing through the sewing machine apparatus.

To obviate this problem, the invention provides for the further reduction of the filament to a second and smaller diameter by a moderate drafting action accomplished by moving filament 13 one or more times around a single godet roll 14, and a companion idler roll 14A maintained at room temperature of about 80F. During this movement the diameter of the filament is suitably reduced, for example, to about 0006-0008 inch which is found to be small enough to be used with conventional needles, but still large enough to be readily visible in the sewn fabric. Furthermore. the filaments after passage from roll 14 preferably are wound immediately upon conventional bobbins 15 by the usual winding apparatus. 1f desired, the filaments may be lubricated by passing through a bath 16 of lubricant the sole purpose of which is to aid in the winding and the later use of the thread in the sewing apparatus and not for modification of the characteristics inherent in the described thread.

The filament thus being wound has, for example, the described uniform diameter substantially free of any nodular portions and with a denier of 230; a strength of 1.20 grams per denier; and a tensile strength of 15,500 psi. It is comparatively soft to the touch and is lacking in significant wiryness. Surprisingly, it is found that in addition to being highly reactive to perchlorethylene it also possesses a reduced shrinkability characteristic as well as a tendency to break with comparatively smooth edges. In order to establish the optimum range for the method of manufacturing, various drawing ratios for the filament passing over roll 14 were tested so as to provide filament samples ranging from percent to 150 percent of residual extension to break and the results found in Table 1 were obtained.

In testing the shrinkage each sample about one yard in length was immersed in boiling water for 2 minutes and the percentage of shrinkage measured.

In testing the reactivity time the sample with a /2 gram weight thereon was immersed in a beaker of perchlorethylene and the elapsed time until break was noted.

As will be understood, when plastic basting thread is to be removed from garments during dry cleaning the garment normally is tumbled in a dry cleaning machine, preferably during a short cycle of 4 to 15 minutes of time and during this immersion the fracturing and loosening of each segment of that thread from the fabric is required. Portions of the thread may be deeply embed ded in the fabric and receive only fleeting contacts with the solvent, thus making it important that the thread be highly reactive to that solvent during such brief contact. Furthermore, ifthe thread has an inherent tendency to shrink, the manufacture of garments requiring passing of basted parts with irons or steam presses prior to removal of the basting thread may result in an unsightly puckered appearance of the assembled garment.

Accordingly, the fact that the thread has both the highest reactivity to the solvent and the least shrinkage. when it has its greater residual extensions to break. is beneficial. Moreover, since retention of a high percentage of extension to break permits use of only a single godet roll, a substantially less expensive arrangement of apparatus may be employed in manufacturing the thread. For average clothing manufacturing practices a basting thread of the type described, therefore, is satisfactory if it possesses at least about percent and not more than about percent of residual extension to break.

A further advantage of this invention may be noted by reference to FIGS. 2 to 3A. The phenomena in volved in the attack of the thread molecules by perchlorethylene are not apparent, but as set forth in the aforementioned Myers patent it is known that during the dry cleaning step the thread fractures and that most of the fragments are thrown from the fabric in which it has been sewn. However, in some instances hook like fragments or fragments with split ends remain embedded in the fabric and necessitate brushing or picking of the same from the fabric. When using conventional basting thread ofthe type disclosed in that patent it was noted that localized strains 20 induced in the filament at a thread loop (FIG. 3) by. for example, the stress at the needle eye, resulted in localized resistance to solvent attack and could be observed in a polarizing mi croscope as strain lines. When such a loop was attacked by the solvent the break thereafter occured to one side of the loop and with jagged ends of the broken thread as indicated in FIG. 3A. The larger fragment 21 of the loop then formed a hook portion which often was difficult to extricate from the fabric.

In like manner it was found that a straight fragment of such thread, as seen in FIG. 2, normally would fracture with jagged ends 22,23 which often remained engaged with the fabric. By contrast, the present thread with its substantial elongation to break does not appear to receive and retain significant localized strains during the sewing operations and when the break occurs the ends ofthe broken thread are relatively smooth as indicated at 24,25 (F16. 2A). In general the higher the reactivity of the thread to the solvent, the smoother will be the fractured ends. As a result of using the improved thread of the present invention removal of thread fragments from the fabric is more effectively accomplished.

The following Examples illustrate the utility of the invention;

EXAMPLE A A bath of polycarbonate pellets available from Mobay Chemical Co. and identified by the trademark MERLON was melt-extruded at 520F. with a diameter of 0.040 inch; passed around a single godet roll at room temperature to reduce the diameter of the filament to about 0.007 inch; and promptly wound without further treatment upon a bobbin. The thread had an elongation to break of 135 percent. For testing purposes, other threads of the same material were prepared with differing percentages of elongation to break as indicated in Table l.

A spool of the thread with 135 percent elongation to break was sewn into coats being manufactured at a commercial clothing factory by means of machine employed in making first facing bastes, second facing bastes, lining bastes, yoke bastes, armhole bastes, and edge bastes made with chain stitch machines.

When these coats were subjected to agitation in a commercial dry cleaning machine using a bath of perchlorethylene and for a cycle period of about minutes they were found by visual inspection upon removal from the machine to be completely free of basting thread.

The operators of the sewing machines found the thread to be softer and less kinky than conventional plastic basting threads and encountered no significant thread breaking problems in conducting their basting operations.

EXAMPLE B A comparative test of two threads was made by sewing five rows ofa first thread with an extension to break of only 35 percent on one portion of a soft flannel vest and with five rows of a second thread having an extension to break of 135 percent on another portion of the same vest spaced from the first portion. The vest was then gently agitated by hand while immersed for 80 seconds in a bath of perchlorethylene. After drying it was visually examined and found that about 80-85 percent of the first thread remained visible in the garment whereas only about 1 percent of the second thread could be detected.

EXAMPLE C Several seams of a first thread having about 0% extension to break were sewn in a knitted fabric article and several seams of a second thread having 135% extension to break were sewn in another portion of the article. The article was then pressed by hand using a pressing cloth and a steam iron. After pressing it was found that the seams made with the first thread gave a distinct puckered appearance while the seams made with the second thread were smooth.

While the foregoing descriptions have been made with respect to certain specific embodiments of the present invention, it is to be understood that changes and modifications may be made without departing from the scope and spirit of the invention as defined in the appended claims.

What is claimed is:

1. A basting thread comprising a monofilament of the polycarbonate 2,2-(4,4- dihydroxydiphenyl) propane substantially devoid of nodular portions along its length and possessing an extension to break amounting to not less than about percent and not more than about 150 percent of its original length, said thread being characterized by its high solvent reactivity to perchlorethylene and by its reduced shrinkage when subjected to heat and by its ability to break with substantially smooth ends when in contact with perchlorethylene for a period of not more than about 2.5 seconds.

2. A thread as defined in claim 1 characterized by having a shrinkage of not more than about 5.90 percent of its original length when immersed in boiling water for 2 minutes.

3. The method of manufacturing basting thread comprising, extruding a length of molten filament of the polycarbonate 2,2(4,4- dihydroxydiphenyl) propane with a first diameter, effecting a plastic flow deformation of the filament and terminating the deformation when the filament acquires a second and smaller diameter characterized by its uniformity of diameter and the absence of nodular portions along its length, and winding the filament upon a spool while the filament possesses an extension to break of not less than about 85 percent and not more than about percent of its original length.

4. The method as defined in claim 3 wherein the step of plastic flow deformation is conducted at approximately room temperature. 

2. A thread as defined in claim 1 characterized by having a shrinkage of not more than about 5.90 percent of its original length when immersed in boiling water for 2 minutes.
 3. The method of manufacturing basting thread comprising, extruding a length of molten filament of the polycarbonate 2,2(4, 4''- dihydroxydiphenyl) propane with a first diameter, effecting a plastic flow deformation of the filament and terminating the deformation when the filament acquires a second and smaller diameter characterized by its uniformity of diameter and the absence of nodular portions along its length, and winding the filament upon a spool while the filament possesses an extension to break of not less than about 85 percent and not more than about 135 percent of its original length.
 4. The method as defined in claim 3 wherein the step of plastic flow deformation is conducted at approximately room temperature. 